If you can't see any residue on the cpu pins, then you're ok. The isopropyl alcohol will dry quickly leaving no residue. And the cpu is low voltage, so it won't smoke. Just be sure it installs easily with no force.
Thanks! I checked it out with one of those sewing magnifying glasses and it looks like there's nothing there; at least not on the pins--it's hard to see if theres anything on the bottom.